The hot gases in a gas turbine often can be at a temperature higher than the melting point of the metal components. To contain the hot gas above the tips of the rotating turbine buckets, segmented cooled stationary shrouds are generally needed. It is therefore necessary to establish a cooling scheme to protect these components during operation.
Turbine shrouds often are cooled by conduction, impingement cooling, film cooling, or combinations thereof. One cooling scheme is shown in commonly owned U.S. Pat. No. 6,390,769. As is shown, this shroud uses a series of four impingement cooled chambers. Each chamber has an impingement baffle that is welded to the inner shroud casting. This arrangement provides a controlled path and distribution for the steam coolant to be sprayed onto the backside of the gas path wall, collected, and then repeated in each of the chambers. Although this method is effective for cooling, the shroud has numerous parts and accompanying manufacturing process steps. U.S. Pat. No. 6,390,769 is incorporated herein by reference.
Thus, there is a desire for an improved inner shroud that provides effective cooling with simplified manufacturing methods and techniques. The shroud should not reduce the overall efficiency of the turbine as a whole.